Hydrodesulfurization (HDS) is a widely-used chemical process which uses catalysts to generate the reaction of hydrogen to remove sulfur and sulfur-contained components from petroleum during refining. The process addresses critical environmental and processing issues. First, the hydrodesulfurization process is required to prevent catalyst poisoning such as in reforming or in a car's catalytic converter. Second, sulfur reduction is necessary to meet environment specification in products such as gasoline or diesel.
New regulations went into effect in 2006 limiting the amount of total sulfur in diesel fuel to 15 ppm at the retail station. Refinery sulfur targets are currently 10 ppm or less to account for pick up of sulfur in the supply and distribution system. These lower sulfur specifications increase hydrotreating severity leading to decreased catalyst life and increased unit maintenance costs. Certain sulfur compounds or classes of compounds are more difficult to hydrotreat due to location of the sulfur on the molecule. The sulfur atom is sterically hindered in the molecule, and reaction with the hydrotreating catalyst may be significantly constrained. We have developed a unique way to quantify the amount and type of these compounds in the feed using a gas analyzer and a sulfur specific analyzer, and then use this data to optimize operation of the hydrotreating unit.
Other objects and advantages of the present invention will become apparent to those skilled in the art upon a review of the following detailed description of the preferred embodiments and the accompanying drawings.